1. Field of the Disclosure
The technology of the disclosure relates to distributed antenna and communications systems, including mobile distributed telecommunication systems and networks, for distributing communications signals to remote antenna units. The distributed antenna and communications systems can include any type of media, including but not limited to optical fiber to provide an optical fiber-based distributed antenna system.
2. Technical Background
Wireless communication is rapidly growing, with ever-increasing demands for high-speed mobile data communication. As an example, so-called “wireless fidelity” or “WiFi” systems and wireless local area networks (WLANs) are being deployed in many different types of areas (e.g., coffee shops, airports, libraries, etc.). Distributed antenna systems communicate with wireless devices called “clients” or “client devices,” which must reside within the wireless range or “cell coverage area” in order to communicate with an access point device. A distributed antenna system (DAS) comprises multiple antennas connected to a common cellular base station and can provide cellular coverage over the same area as a single antenna.
One approach to deploying a distributed antenna system involves the use of radio frequency (RF) antenna coverage areas, also referred to as “antenna coverage areas.” Antenna coverage areas can have a radius in the range from a few meters up to twenty meters as examples. Combining a number of access point devices creates an array of antenna coverage areas. Because the antenna coverage areas each cover a small area, there are typically only a few users (clients) per antenna coverage area. This allows for minimizing the amount of RF bandwidth shared among the wireless system users.
A distributed antenna system can be implemented to provide adequate cellular telephone and internet coverage within an area where the propagation of an RF signal is disturbed. For example, transmission and reception of RF signals are often blocked inside high buildings due to thick steel, concrete floors and walls. Similar problems can be found in other areas such as airports, shopping malls or tunnels, etc. To overcome this coverage problem, a distributed antenna system may comprise components that receive an input RF signal and convert it to a wired signal, for example, an optical signal. The distributed antenna system may include fiber optic cables to transmit optical signals in an area where RF signals are blocked, e.g., inside the buildings. The antennas can be placed close to the possible locations of mobile or portable terminals, originated from a utility or service room and then arranged to form a star-like topology. The distributed antenna system may also comprise components that re-convert the wired signals back to the RF signals.
As discussed above, it may be desired to provide such distributed antenna systems indoors, such as inside a building or other facility, to provide indoor wireless communication for clients. Otherwise, wireless reception may be poor or not possible for wireless communication clients located inside the building. In this regard, the remote antenna units can be distributed throughout locations inside a building to extend wireless communication coverage throughout the building. While extending the remote antenna units to locations in the building can provide seamless wireless coverage to wireless clients, other services may be negatively affected or not possible due to the indoor environment. For example, it may be desired or required to determine the location of client devices or provide localization services for client devices, such as emergency 911 (E911) services as an example. If the client device is located indoors, techniques such as global positioning services (GPSs) may not be possible to determine the location of the client device. Further, triangulation techniques may not be able to determine the location of the client device due to the remote antenna units typically being arranged to avoid overlapping regions between antenna coverage areas.